| File: | jdk/src/java.base/unix/native/libjsig/jsig.c |
| Warning: | line 155, column 7 Value stored to 'sigblocked' is never read |
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| 1 | /* |
| 2 | * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved. |
| 3 | * Copyright (c) 2012, 2015 SAP SE. All rights reserved. |
| 4 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 5 | * |
| 6 | * This code is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License version 2 only, as |
| 8 | * published by the Free Software Foundation. Oracle designates this |
| 9 | * particular file as subject to the "Classpath" exception as provided |
| 10 | * by Oracle in the LICENSE file that accompanied this code. |
| 11 | * |
| 12 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 13 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 14 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 15 | * version 2 for more details (a copy is included in the LICENSE file that |
| 16 | * accompanied this code). |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License version |
| 19 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 20 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 21 | * |
| 22 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| 23 | * or visit www.oracle.com if you need additional information or have any |
| 24 | * questions. |
| 25 | * |
| 26 | */ |
| 27 | |
| 28 | /* This is a special library that should be loaded before libc & |
| 29 | * libthread to interpose the signal handler installation functions: |
| 30 | * sigaction(), signal(), sigset(). |
| 31 | * Used for signal-chaining. See RFE 4381843. |
| 32 | * Use of signal() and sigset() is now deprecated as these old API's should |
| 33 | * not be used - sigaction is the only truly supported API. |
| 34 | */ |
| 35 | |
| 36 | #include "jni.h" |
| 37 | |
| 38 | #include <dlfcn.h> |
| 39 | #include <errno(*__errno_location ()).h> |
| 40 | #include <pthread.h> |
| 41 | #include <signal.h> |
| 42 | #include <stdio.h> |
| 43 | #include <stdlib.h> |
| 44 | #include <string.h> |
| 45 | |
| 46 | #if (__STDC_VERSION__199901L >= 199901L) |
| 47 | #include <stdbool.h> |
| 48 | #else |
| 49 | #define bool_Bool int |
| 50 | #define true1 1 |
| 51 | #define false0 0 |
| 52 | #endif |
| 53 | |
| 54 | #define MAX_SIGNALS(64 + 1) NSIG(64 + 1) |
| 55 | |
| 56 | static struct sigaction sact[MAX_SIGNALS(64 + 1)]; /* saved signal handlers */ |
| 57 | |
| 58 | static sigset_t jvmsigs; /* Signals used by jvm. */ |
| 59 | |
| 60 | #ifdef MACOSX |
| 61 | static __thread bool_Bool reentry = false0; /* prevent reentry deadlock (per-thread) */ |
| 62 | #endif |
| 63 | |
| 64 | /* Used to synchronize the installation of signal handlers. */ |
| 65 | static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER{ { 0, 0, 0, 0, 0, 0, 0, { 0, 0 } } }; |
| 66 | static pthread_cond_t cond = PTHREAD_COND_INITIALIZER{ { {0}, {0}, {0, 0}, {0, 0}, 0, 0, {0, 0} } }; |
| 67 | static pthread_t tid; |
| 68 | |
| 69 | typedef void (*sa_handler_t)(int); |
| 70 | typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); |
| 71 | typedef sa_handler_t (*signal_function_t)(int, sa_handler_t); |
| 72 | typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); |
| 73 | |
| 74 | static signal_function_t os_signal = 0; /* os's version of signal()/sigset() */ |
| 75 | static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ |
| 76 | |
| 77 | static bool_Bool jvm_signal_installing = false0; |
| 78 | static bool_Bool jvm_signal_installed = false0; |
| 79 | |
| 80 | |
| 81 | static void signal_lock() { |
| 82 | pthread_mutex_lock(&mutex); |
| 83 | /* When the jvm is installing its set of signal handlers, threads |
| 84 | * other than the jvm thread should wait. */ |
| 85 | if (jvm_signal_installing) { |
| 86 | /* tid is not initialized until jvm_signal_installing is set to true. */ |
| 87 | if (pthread_equal(tid, pthread_self()) == 0) { |
| 88 | do { |
| 89 | pthread_cond_wait(&cond, &mutex); |
| 90 | } while (jvm_signal_installing); |
| 91 | } |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | static void signal_unlock() { |
| 96 | pthread_mutex_unlock(&mutex); |
| 97 | } |
| 98 | |
| 99 | static sa_handler_t call_os_signal(int sig, sa_handler_t disp, |
| 100 | bool_Bool is_sigset) { |
| 101 | sa_handler_t res; |
| 102 | |
| 103 | if (os_signal == NULL((void*)0)) { |
| 104 | // Deprecation warning first time through |
| 105 | printf(HOTSPOT_VM_DISTRO " VM warning: the use of signal() and sigset() "__printf_chk (2 - 1, "OpenJDK" " VM warning: the use of signal() and sigset() " "for signal chaining was deprecated in version 16.0 and will " "be removed in a future release. Use sigaction() instead.\n" ) |
| 106 | "for signal chaining was deprecated in version 16.0 and will "__printf_chk (2 - 1, "OpenJDK" " VM warning: the use of signal() and sigset() " "for signal chaining was deprecated in version 16.0 and will " "be removed in a future release. Use sigaction() instead.\n" ) |
| 107 | "be removed in a future release. Use sigaction() instead.\n")__printf_chk (2 - 1, "OpenJDK" " VM warning: the use of signal() and sigset() " "for signal chaining was deprecated in version 16.0 and will " "be removed in a future release. Use sigaction() instead.\n" ); |
| 108 | if (!is_sigset) { |
| 109 | os_signal = (signal_function_t)dlsym(RTLD_NEXT((void *) -1l), "signal"); |
| 110 | } else { |
| 111 | os_signal = (signal_function_t)dlsym(RTLD_NEXT((void *) -1l), "sigset"); |
| 112 | } |
| 113 | if (os_signal == NULL((void*)0)) { |
| 114 | printf("%s\n", dlerror())__printf_chk (2 - 1, "%s\n", dlerror()); |
| 115 | exit(0); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | #ifdef MACOSX |
| 120 | /* On macosx, the OS implementation of signal calls sigaction. |
| 121 | * Make sure we do not deadlock with ourself. (See JDK-8072147). */ |
| 122 | reentry = true1; |
| 123 | #endif |
| 124 | |
| 125 | res = (*os_signal)(sig, disp); |
| 126 | |
| 127 | #ifdef MACOSX |
| 128 | reentry = false0; |
| 129 | #endif |
| 130 | |
| 131 | return res; |
| 132 | } |
| 133 | |
| 134 | static void save_signal_handler(int sig, sa_handler_t disp, bool_Bool is_sigset) { |
| 135 | sigset_t set; |
| 136 | |
| 137 | sact[sig].sa_handler__sigaction_handler.sa_handler = disp; |
| 138 | sigemptyset(&set); |
| 139 | sact[sig].sa_mask = set; |
| 140 | sact[sig].sa_flags = 0; |
| 141 | } |
| 142 | |
| 143 | static sa_handler_t set_signal(int sig, sa_handler_t disp, bool_Bool is_sigset) { |
| 144 | sa_handler_t oldhandler; |
| 145 | bool_Bool sigused; |
| 146 | bool_Bool sigblocked; |
| 147 | |
| 148 | signal_lock(); |
| 149 | |
| 150 | sigused = sigismember(&jvmsigs, sig); |
| 151 | if (jvm_signal_installed && sigused) { |
| 152 | /* jvm has installed its signal handler for this signal. */ |
| 153 | /* Save the handler. Don't really install it. */ |
| 154 | if (is_sigset) { |
| 155 | sigblocked = sigismember(&(sact[sig].sa_mask), sig); |
Value stored to 'sigblocked' is never read | |
| 156 | } |
| 157 | oldhandler = sact[sig].sa_handler__sigaction_handler.sa_handler; |
| 158 | save_signal_handler(sig, disp, is_sigset); |
| 159 | |
| 160 | signal_unlock(); |
| 161 | return oldhandler; |
| 162 | } else if (jvm_signal_installing) { |
| 163 | /* jvm is installing its signal handlers. Install the new |
| 164 | * handlers and save the old ones. jvm uses sigaction(). |
| 165 | * Leave the piece here just in case. */ |
| 166 | oldhandler = call_os_signal(sig, disp, is_sigset); |
| 167 | save_signal_handler(sig, oldhandler, is_sigset); |
| 168 | |
| 169 | /* Record the signals used by jvm */ |
| 170 | sigaddset(&jvmsigs, sig); |
| 171 | |
| 172 | signal_unlock(); |
| 173 | return oldhandler; |
| 174 | } else { |
| 175 | /* jvm has no relation with this signal (yet). Install the |
| 176 | * the handler. */ |
| 177 | oldhandler = call_os_signal(sig, disp, is_sigset); |
| 178 | |
| 179 | signal_unlock(); |
| 180 | return oldhandler; |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | JNIEXPORT__attribute__((visibility("default"))) sa_handler_t signal(int sig, sa_handler_t disp) { |
| 185 | if (sig < 0 || sig >= MAX_SIGNALS(64 + 1)) { |
| 186 | errno(*__errno_location ()) = EINVAL22; |
| 187 | return SIG_ERR((__sighandler_t) -1); |
| 188 | } |
| 189 | |
| 190 | return set_signal(sig, disp, false0); |
| 191 | } |
| 192 | |
| 193 | JNIEXPORT__attribute__((visibility("default"))) sa_handler_t sigset(int sig, sa_handler_t disp) { |
| 194 | #ifdef _ALLBSD_SOURCE |
| 195 | printf("sigset() is not supported by BSD")__printf_chk (2 - 1, "sigset() is not supported by BSD"); |
| 196 | exit(0); |
| 197 | #else |
| 198 | if (sig < 0 || sig >= MAX_SIGNALS(64 + 1)) { |
| 199 | errno(*__errno_location ()) = EINVAL22; |
| 200 | return (sa_handler_t)-1; |
| 201 | } |
| 202 | |
| 203 | return set_signal(sig, disp, true1); |
| 204 | #endif |
| 205 | } |
| 206 | |
| 207 | static int call_os_sigaction(int sig, const struct sigaction *act, |
| 208 | struct sigaction *oact) { |
| 209 | if (os_sigaction == NULL((void*)0)) { |
| 210 | os_sigaction = (sigaction_t)dlsym(RTLD_NEXT((void *) -1l), "sigaction"); |
| 211 | if (os_sigaction == NULL((void*)0)) { |
| 212 | printf("%s\n", dlerror())__printf_chk (2 - 1, "%s\n", dlerror()); |
| 213 | exit(0); |
| 214 | } |
| 215 | } |
| 216 | return (*os_sigaction)(sig, act, oact); |
| 217 | } |
| 218 | |
| 219 | JNIEXPORT__attribute__((visibility("default"))) int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { |
| 220 | int res; |
| 221 | bool_Bool sigused; |
| 222 | struct sigaction oldAct; |
| 223 | |
| 224 | if (sig < 0 || sig >= MAX_SIGNALS(64 + 1)) { |
| 225 | errno(*__errno_location ()) = EINVAL22; |
| 226 | return -1; |
| 227 | } |
| 228 | |
| 229 | #ifdef MACOSX |
| 230 | if (reentry) { |
| 231 | return call_os_sigaction(sig, act, oact); |
| 232 | } |
| 233 | #endif |
| 234 | |
| 235 | signal_lock(); |
| 236 | |
| 237 | sigused = sigismember(&jvmsigs, sig); |
| 238 | if (jvm_signal_installed && sigused) { |
| 239 | /* jvm has installed its signal handler for this signal. */ |
| 240 | /* Save the handler. Don't really install it. */ |
| 241 | if (oact != NULL((void*)0)) { |
| 242 | *oact = sact[sig]; |
| 243 | } |
| 244 | if (act != NULL((void*)0)) { |
| 245 | sact[sig] = *act; |
| 246 | } |
| 247 | |
| 248 | signal_unlock(); |
| 249 | return 0; |
| 250 | } else if (jvm_signal_installing) { |
| 251 | /* jvm is installing its signal handlers. Install the new |
| 252 | * handlers and save the old ones. */ |
| 253 | res = call_os_sigaction(sig, act, &oldAct); |
| 254 | sact[sig] = oldAct; |
| 255 | if (oact != NULL((void*)0)) { |
| 256 | *oact = oldAct; |
| 257 | } |
| 258 | |
| 259 | /* Record the signals used by jvm. */ |
| 260 | sigaddset(&jvmsigs, sig); |
| 261 | |
| 262 | signal_unlock(); |
| 263 | return res; |
| 264 | } else { |
| 265 | /* jvm has no relation with this signal (yet). Install the |
| 266 | * the handler. */ |
| 267 | res = call_os_sigaction(sig, act, oact); |
| 268 | |
| 269 | signal_unlock(); |
| 270 | return res; |
| 271 | } |
| 272 | } |
| 273 | |
| 274 | /* The three functions for the jvm to call into. */ |
| 275 | JNIEXPORT__attribute__((visibility("default"))) void JVM_begin_signal_setting() { |
| 276 | signal_lock(); |
| 277 | sigemptyset(&jvmsigs); |
| 278 | jvm_signal_installing = true1; |
| 279 | tid = pthread_self(); |
| 280 | signal_unlock(); |
| 281 | } |
| 282 | |
| 283 | JNIEXPORT__attribute__((visibility("default"))) void JVM_end_signal_setting() { |
| 284 | signal_lock(); |
| 285 | jvm_signal_installed = true1; |
| 286 | jvm_signal_installing = false0; |
| 287 | pthread_cond_broadcast(&cond); |
| 288 | signal_unlock(); |
| 289 | } |
| 290 | |
| 291 | JNIEXPORT__attribute__((visibility("default"))) struct sigaction *JVM_get_signal_action(int sig) { |
| 292 | /* Does race condition make sense here? */ |
| 293 | if (sigismember(&jvmsigs, sig)) { |
| 294 | return &sact[sig]; |
| 295 | } |
| 296 | return NULL((void*)0); |
| 297 | } |